The invention relates to a valve for atomizing a fluid, in particular an injection and/or metering valve for fuel injection or exhaust systems in internal combustion engines.
In a known fuel injection valve for fuel injection systems of internal combustion engines (DE 10 2006 041 475 A1), the inflow cavity is formed, as a circular recess, into that end surface of the valve seat body which faces toward the spray hole disk, and said inflow cavity extends over the valve opening and over those openings of the spray holes in the spray hole disk which face toward the valve seat carrier. The hole axes of the spray holes are aligned parallel to one another and to the axis of the valve seat body. The spray holes, which are arranged on a pitch circle, all have the same shape, the contour of which is triangular, in the form of a truncated triangle, semicircular, in the form of a truncated semicircle, semielliptical, in the form of a truncated semiellipse, in the form of a triangle truncated in a rounded manner, semicircular or semielliptical with rounded inlet edges, or of similar design. Here, all the spray hole shapes are contoured such that a tapering of the spray hole is provided on the side opposite the inflow side, that is to say radially outward. As a result of said contour, the fluid jet which fans out directly after exiting the spray hole is constricted again in the radially outer region, such that comparatively large droplets remain as an envelope in the outer region of the ejected fluid hollow conical lamella. In internal combustion engines with intake pipe injection, it is achieved by means of this spray hole geometry that, in the first start cycles (cold start) of the internal combustion engine with externally-applied ignition, the outer droplets of the ejected fuel spray are deposited as wall film on the intake pipe walls. In this way, in the first start cycles, only the finely atomized droplets which are present in the center of the jet, and a correspondingly high fuel vapor component, pass directly into the combustion chamber, and the poorly prepared mixture component is supplied to the combustion chamber only after a delay, such that the best-prepared mixture component is introduced into the combustion chamber in the start cycle, and the exhaust-gas emissions are considerably reduced during this time.